Biguanide compounds such as metformin and the like are effective for the treatment of non-insulin dependent diabetes mellitus and the like, and have been widely used for the superior efficacy thereof. As preparation, tablets are now in the market in Japan, Europe etc. and tablets and solutions are now in the market in the US.
In the biguanide compounds such as metformin and the like, tablets are bulky due to the high dose, which renders administration to the elderly, children and the like difficult. In diabetic patients, moreover, the dose often needs to be varied. However, control of the dose according to the symptom is difficult with tablets. While solutions are easy administration preparations which enable control of the dose, they are inferior to a solid preparation in the aspects of chemical stability, hygiene such as bacteriological control and the like. Granular preparations are easy to take, facilitate control of the dose, show good stability as compared to solutions because they are solids, and are associated with less hygiene problems.
As granular preparations of biguanide compounds such as metformin and the like, for example, patent reference 1 discloses preparations for oral administration (fine granules and granules) consisting of a biguanide compound and an organic acid.
As a method for preventing solidification of a granular or powder preparation, for example, patent reference 2 discloses a powder preparation for a restoration of compromised skin, which consists of sucrose, povidone-iodine, and a water-soluble carrier polymer selected from polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid or a salt thereof, pullulan, carboxyvinyl polymer, methylcellulose, hydroxymethylcellulose, hydroxypropylmethylcellulose and carboxymethylcellulose or a salt thereof.
It is well known that selection of a solidification-preventive agent for a granular or powder preparation depends on the contained drug, and is an important issue. However, the above-mentioned references and the like do not at all disclose information relating to the solidification-preventive effect of the combination of a particular water-soluble carrier polymer or an inorganic compound and a particular drug, particularly a biguanide compound.
Pullulan is used as a base, a binder, a coating agent, a sugar coating agent or a diluent for use as a pharmaceutical additive, and used as a binder, a thickening agent, a moisturing agent, a film agent and the like for use as a food additive. Dextrin is used as an adsorbent, a binder, an adhesive, a thickening agent, a diluent, a dispersing agent and a disintegrant for use as a pharmaceutical additive. However, there is found no embodiment where pullulan or dextrin is used as a solidification-preventive agent of a granular preparation.    patent reference 1: JP-A-2002-512953    patent reference 2: JP-A-8-12582